Phase II trials showed that the drug reduced the average daily OFF time - characterised by a re-emergence of PD motor symptoms such as impaired ability to move - when added to treatment regimens including levodopa/carbidopa.

Tozadenant represents “a compelling opportunity with potential market exclusivity to 2030,” said the US group’s chief executive Ron Cohen, noting that a US filing is being targeted by the end of 2018.

“Approximately 350,000 people with Parkinson’s in the US experience OFF periods, and if approved, tozadenant could provide a much needed treatment option,” he added.

The deal also gives Acorda access to SYN120, an oral, 5-HT6/5-HT2A dual receptor antagonist for Parkinson’s-related dementia, in Phase II development with support from the Michael J. Fox Foundation, and BTT1023, a fully human monoclonal antibody in Phase II development for treatment of the chronic liver disease primary sclerosing cholangitis.